Reversible discharge flow variable displacement pump



May 26, 1964 s. v. SMITH 3,

REVERSIBLE DISCHARGE FLOW VARIABLE DISPLACEMENT PUMP Filed Feb. 10, 1959 2 Sheets-Sheet 1 IN VEN TOR.

May 26, 1964 s. v. SMITH 3,

REVERSIBLE DISCHARGE FLOW VARIABLE DISPLACEMENT PUMP Filed Feb. 10, 1959 2 Sheets-Sheet 2 6 a w L 1 7 85 9 102 4 a; 2&4 \l 9i i 50/1/1051. 75/14/774. INVENTOR.

United States Patent ice 3,134,334 REVERSIBLE DISCHARGE FLGW VARIABLE DISPLACEMENT P Ult il Samuel V. Smith, Long Beach, Calif., assignor, by mesne assignments, to Fluid Power Products, ERIC. a corporation of Caiifornia Filed Feb. 10, 1959, Ser. No. 792,354 16 Claims. (Cl. 103-120) The present invention relates generally to the field of pumps, and more particularly to a variable displacement pump by means of which it is not only possible to control the rate of fluid discharge, but the direction of flow of fluid from the pump may also be reversed, with either or both of these adjustments being possible while the pump is operating.

A major object of the present invention is to supply a pump that is capable of supplying fluid at any desired rate of flow within a predetermined range by a simple adjustment that may be made to the pump while it is operating, which pump also permits reversal of the direction of fluid flow from the pump during operation thereof by the same means employed in controlling the rate of fluid discharge therefrom. Variation in the rate of fluid discharge from the pump and reversal of the direction of flow of discharged fluid is attained by moving a portion of the elements comprising the pump combination, which eliminates the necessity of resorting to in tricate piping and valving heretofore requiredfor this purpose in present-day pump installations.

Another object of the invention is to provide a pump which is of a relatively simple structure, is compact, requires a minimum of maintenance attention, and one that will supply a steady, reliable source of fluid under a desired pressure to actuate such mechanisms as hydraulically operated oil well pumping units, and numerous other mechanisms in which portions thereof are reciprocated at a first rate in one direction and at a second rate in an opposite direction.

A still further object of the invention is to supply a pump that is particularly well adapted to supply fluid at a desired pressure and at a desired rate and direction of flow which varies through a sequence of steps comprising a cycle, with the adjustment of the pump to provide this sequence of steps in a cycle wherein the rate of flow and direction of flow is altered, being attained by either mechanical, hydraulic, electrical or manual means.

These and other objects and advantages of the invention will become apparent from the following description of a preferred form thereof, and from the accompanying drawings illustrating that form, in which:

FIGURE 1 is a top plan view of the pump;

FIGURE 2 is a vertical cross-sectional view of the pump taken on line 22 of FIGURE 1;

FIGURE 3 is a combined top plan view and transverse cross-sectional view of the pump taken on line 3-3 of FIGURE 2;

FIGURE 4 is a fragmentary vertical cross-sectional view of the pump taken on line 4-4 of FIGURE 3;

FIGURE 5 is a fragmentary vertical cross-sectional view of the pump taken on line 55 of FIGURE 3; and

FIGURE 6 is an. exploded perspective view of the pump.

Referring to FIGURES 2, 3 and 6 of the drawings for the general arrangement of the pump,'it will be seen to include a driven shaft A having a cylindrical rotor B fixedly mounted intermediately thereon. Rotor B has a number of circumferentially spaced, radially extending slots C formed therein, and a flat rectangular blade D is slidably mounted in each of these slot s A ring E is provided which is of substantially the same 3,134,334 Patented May 26, 1964 width as that of blades D, but is substantially larger in diameter than rotor B, as may be seen in FIGURE 6.

The slide block, generally identified by the letter F, includes a circular member G which has two diametrically opposed pistons H projecting therefrom. Intermediately located between pistons H and projecting from member G are two guide blocks I that have parallel faces. Two flanged cylinders K-l and K-2 are provided that are open on the adjacent ends thereof, and the interior of these cylinders are of such diameter as to permit pistons H to snugly and slidably fit therein.

A pump housing L is also provided which preferably comprises two substantially identical halves L-l and L-2, which When assembled in abutting contact, sealingly engage cylinders K-l and K-Z, as may be seen in FIG- URES 1, 3 and 6. Halves L-l and L2 are of such structure that together with slide block F, circular member G, pistons H, cylinders K, and sealing means X to be described hereinafter, they cooperatively define two separate compartments M and N of substantially the same shape that are situated within housing L. A first fluidcarrying sleeve 0 is sealingly engaged by the housing halves L1 and L2, and is atall times in communication with the first compartment M. A second fluid-carrying sleeve P is also sealingly held by the housing halves L-I and L-2, is circumferentially separated from the. first sleeve, and is at all times in communication with the second compartment N.

When the rotor B is rotated in a counter clockwise direction (FIGURE 3), and fiuid is admitted through sleeve 0 into compartment M and the slide block F has been moved the maximum distance toward clinder K-2, fluid in the compartmnt enters the spaces S defined between blades D and the interior surface of ring E to be positively displaced from compartment M into compartment N. As this fluid displacement continues from the first to the second compartment, the fluid pressure in compartment N builds up to cause discharge of the fluid from second sleeve P. By moving the slide block F away from the flanged cylinder K-Z by means which will later be described in detail, the space in each of spaces S is decreased and the rate at which fluid is discharged from compartment M to compartment N is decreased, assuming, of course, that the rate of rotation of shaft A remains constant. When slide block F is moved a maximum distance away from second cylinder K2, the space S adjacent this cylinder is completely eliminated, with spaces S of maximum size then being defined by blades D and the interior surface of ring E adjacent the first flanged cylinder K-l.

The direction of rotation of rotor B remains the same, and fluid is then withdrawn from second compartment N to be positively carried from spaces S into first compartment N. The pressure on the fluid in the first compartment increases and causes the fluid to discharge through first sleeve 0. Thus it will be seen that sleeves O and P can interchangeably serve as fluid inlets and outlets from compartments M and N. Also, by varying the position of slide block F, the rate of discharge from either sleeve 0 or P can be controlled. A pump having the operational characteristics of the one just described is particularly advantageous when used in actuating a hydraulic oil well pumping unit, for fluid can be discharged from one of the sleeves O or P to the unit to cause the hydraulically operated ram to raise the sucker rod at the upstroke rate, and thereafter bleed the fluid used on the upstroke back through the pump by reversing the flow as above described. Due to this control over the rate of fluid flow, the sucker rod can be lowered at a rate different than that used in the raising thereof.

In detail, it will be seen that the shaft A may be connected to any conventional source of power. This shaft comprises a longitudinally extending section of enlarged transverse cross section that is positioned within the confines of housing L, as shown in FIGURE 2. The rotor B is fixedly, yet removably mounted on shaft section It by means of a key 12 that engages complementary longitudinally extending slots 14 and 16 situated in section 10 and the bore of the rotor B, respectively. Rotor B is centrally positioned on shaft section 10, and the projecting portions of section 10 are rotatably supported by a pair of identical roller bearing assemblies 18 and 18'.

As previously mentioned, the pump housing L is made up of two abutting halves L1 and L-2, which are substantially identical in construction. Accordingly, only the pump housing half Ll will be described in detail herein, and in the drawings the corresponding elements of housing half L-2 are identified by the same numerals, but with a prime affixed thereto. Housing half L1, as can best be seen in FIGURES 2, 3 and 6, includes a generally circular side wall 20 that has a cylindrical flange 22 normally disposed relative to the outer circumferential edge portion thereof. The exterior surface of flange 22 develops'into two slightly projecting portions 24 and 26 which terminate in parallel flat faces 24a and 26a. Centrally disposed, coaxially aligned, semi-cylindrical grooves 28 and 30 are formed in portions 24 and 26 respectively (FIGURE 6). Grooves 28 and 30 are adapted to slidably support pistons H therein, as will be explained in detail hereinafter. Two projecting portions 32 and 34 of flange 22 have third and fourth semi-cylindrical grooves 36 and 38 respectively, formed therein that are adapted to be sealingly engaged by the first and second sleeves O and P respectively. The side wall 20, as best seen in FIGURE 2, is formed with an inwardly extending boss 46 from which two elongate extensions 42 and 4-4 project in opposite directions to grooves 28 and 30 respectively.

The upper face of boss 40 and the upper faces of extensions 42 and 44 lie in a common plane, and these extensions terminate at the junction thereof with grooves 28 and 30 in vertical arcuate wall segments 42a and 44a re spectively, as best seen in FIGURE 6. The upper circumferentially extending edge of flange 22 (FIGURE 2) has an upwardly projecting rib 46 that is adapted to interlock with a groove 48 formed in flange 22 for alignment and sealing purposes.

The outer circumferential portion of housing half L-2 is formed with a number of spaced bores 56 extending therethrough as Well as through the flange 22', and are aligned with tapped bores 52 that extend through flange 22 and the outermost portions of side wall 20. Each aligned pair of bores 50 and 52 has a bolt 54 extending therethrough, which when tightened, serves to hold halves L1 and L-2 together, with the adjoining faces of the flanges 22 and 22' being in pressure-abutting contact. The face of flange 22' abutting against flange 22 has a recess 56 formed therein in which a resilient sealing member 58 is compressed and held in fluid-sealing contact with flange 22 when bolts 54 are tightened as shown in FIG- URE 2. Boss 40 projects inwardly to terminate in a flat ring-shaped face 60 in which a circular groove 62 is formed. Slots C in rotor B extend inwardly a suflicient distance to be at all times in communication with groove 62. Boss 40 also has a bore 64 extending therethrough to an extension 66 angularly disposed relative thereto which terminates at groove 62. Threads 68 are formed on the outer portion of bore 64 that are engaged by a threaded plug '71) through which a bore '72 extends, and the inner end of the plug terminates in a ring-shaped tapered seat 74. A ball 76 is positioned in bore 64 and is at all times urged into fluid-sealing contact with seat 74 by a helical spring '78. The plug '70, ball 76, spring 78, bore 64 and extension 66 cooperatively provide a check valve assembly which permits the flow of fluid from compartments M and N to grooves 62 and 62' and into slots C, but prevents discharge of fluid therefrom.

Boss 40 has a relatively large bore 80 extending longitudinally therethrough which is of such diameter that the roller bearing assembly 13 fits snugly within the confines thereof. A helical spring 82 is provided that is at all times compressed, with one end thereof abutting against the roller bearing assembly 18 and the opposite end against a collar 34 that is slidably and rotatably mounted on shaft A. A circumferentially extending groove 86 is formed on the interior face of collar 84 and a ring-shaped resilient sealing member 88 is disposed therein. Movement of collar 34 away from rotor B due to fluid pressure within the pump housing L is prevented by a relatively heavy circular plate 9t) having a centrally disposed bore 92 formed therein through which shaft A extends. A nu1nber of circumferentially spaced bolt holes 94 are formed in plate that are alignable with tapped bores 96 which extend inwardly into side wall 26. Plate 93* is removably held in a fixed position on housing half L-l when the openings 94 and 96 are aligned, and engaged by bolts 98.

Before the two housing halves L1 and L-2 are assembled in abutting contact as shown in FIGURE 2, the two fluid-carrying sleeves O and P are placed within the confines of slots 36 and 38. Sleeves O and P are identical in construction, and therefore only sleeve 0 will be described in detail herein. Sleeve 0 includes a tubular portion 1% having threads 1&2 formed on the exterior thereof. The inwardly disposed end portion of member 196 develops into a slightly enlarged, circumferentially extending ring 103 that is located in an enlarged inner portion 164 of groove 30. The outer surface of ring 103 has a circumferentially extending groove 196 formed therein in which a resilient sealing ring 103 is positioned, and is in sealing contact with a part of the surface defining the enlarged portion 104 above mentioned. Threads are formed on the interior member 190 which permit the connection of an externally threaded conduit (not shown) to sleeve 0. Rotation of sleeve 0 within the confines of grooves 30 and 30' is prevented by a key 116. The adjacent surfaces of tubular member 100 and flange 22' have aligned slots 112 and 114 respectively formed therein that are occupied by the key 116 when the housing halves L-l and L2 are placed in abutting relationship as shown in FIGURE 2. An internally threaded ring-shaped member 118 is caused to engage threads 102, and is tightened thereon to draw the fluid-carrying sleeve 0 outwardly to hold abutting circumferential edge portions of the ring shaped portion 102 and flanges 22 and 22 in pressure contact as shown.

The slide block F, as best seen in FIGURES 3 and 6, has two guide blocks I that are diametrically opposed and intermediately positioned between the two pistons H, and these guide blocks terminate in flat, parallel faces 120. Guide faces 12% at all times slidably engage two pressure plates 122. Each plate 122 has two parallel, longitudinally spaced bores 124 formed therein that are rotatably engaged by threaded projections 126 of stud bolts 128 which extend through tapped bores 130 formed in flanges 22 and 22'. The outer end portions of stud bolts 128 are threadedly engaged by lock nuts 132 that non-rotatably hold the stud bolts in bores 130.

The pressure plates 122 are in such alignment with guide blocks J that the pistons H are truly and slidably aligned within the confines of the flanged cylinders K. The two cylinders K are identical, but for ease in describing the operation of the invention, these cylinders are referred to separately herein by the notations K-l and K-2. As may be seen in FIGURE 6, flanged cylinder K! is adapted to be disposed within the confines of grooves 28, 255, and cylinder K-2 to be situated within grooves 39, 30 when housing halves L-l and L-2 are in abutting contact, as shown in FIGURE 2. Inasmuch as cylinders K-I and K-2 are identical in construction, a detailed description of the structure of flanged cylinder K4 only is given.

Flanged cylinder K1, as best seen in FIGURES 3 and 6, includes a relatively heavy flange 134, the thickness of which is dependent on the maximum pressure of the fluid that will be discharged from the pump. Flange 134 has a number of circumferentially spaced bolt holes 136 formed therein that are alignable with tapped bores 138 formed in the enlarged flange portions 24 and 26. When the bolt holes 136 and tapped bores 138 are engaged by bolts 140, the flanged cylinders K-l, K2 and housing halves L1, L-Z are held together as an integral unit. A boss 142 projects outwardly from each flange 134, and a centrally disposed, longitudinally extending tapped bore 144 is formed therein. A second tapped bore 146 is formed in boss 142 and is angularly disposed relative to bore 144.

Cylinder K-l further includes a cylindrical heavywalled shell 150 that projects outwardly from flange 134 on the side thereof opposite that on which boss 142 is situated. Shell 150 has a bore 152 extending longitudinally therethrough in coaxial alignment with'bore 144 communicating with space 148. A circumferentially extending groove 154 is formed on the exterior surface of shell 15% and has a resilient sealing ring 156 disposed therein. Ring 156 effects a fluid-tight seal between the exterior surface of shell 156 and the interior surfaces of grooves 28, 28' or 39, 30'. Tapped bore 146 is adapted to be connected to an externally threaded tubular fitting 147 which is in turn connected to a conduit 147a that extends to a source (not shown) of hydraulic fluid under pressure. When this fluid under pressure is admitted to the confines of the cylinder K-I it is capable of moving the piston H situated therein in a'direction opposite .to that of the flow of the fluid, assuming that fluid in the opposite cylinder K-Z is permitted to escape therefrom. Fluid escapes from each of the cylinders by flowing therefrom through one of the bores 146. The valving that permits fluid discharge through one of the bores 146 to one of the cylinders K-1 or K2 with concurrent discharge of fluid from the opposite cylinder through the bore 146 associated therewith to permit movement of the slide block F is conventional and hence has not been shown. Each of the bores 144 is engaged by a threaded member 145 that has a head 145a that projects inwardly into one of the cylinders R4 or K2 and acts as a stop to limit the outward movement of the piston H mounted therein. The outwardly projecting end of each threaded member 145 is engaged by a lock nut 14-5b that is tightened to abut against the exterior face of boss 142 to hold member 145 at a desired fixed longitudinal position relative to one of the cylinders K-1 or K-2.

Each piston H (FIGURES 3 and 6) is circular in transverse cross section and terminates on the free end thereof in a downwardly and inwardly tapering ringshaped surface 158. A circumferentially extending groove 160 is formed in each piston H wherein a resilient sealing ring 162 is positioned that is at all times in slidable, fluid-sealing pressure contact with the surface of bore 152. Depending upon the position of the block F, each piston H is at all times disposed adjacent the surfaces of arms 42, 44 and 42', 44', as will be apparent from an examination of the structure of the invention shown in FIGURE 6. To separate the compartments M and N as slide block F and piston H are moved within the confines of housing A to either adjust the rate of fluid discharge or the direction of fluid flow, two identical elongate, longitudinally extending parallel recesses 164 are formed in the exterior surface of each piston H, and each recess slidably and snugly receives an elongate rigid sealing member 166. Recesses 164 are connected by two transversely disposed bores 16%, as may best be seen in FIGURE 4. A compressed helical spring 170 is situated in each bore 168, which at all times urges sealing members 166 away from one another into slidable fluid-sealing contact with the interior surfaces of arms 44, 44' and 42, 42', as well as the innermost surface portions of bores 152. The sealing mechanism above described has been previously gena 6 erally referred to in the specification by the notation sealing means X.

In use, the operation of the invention is extremely simple. Shaft A is connected to a source of rotating power of the necessary magnitude to provide fluid at the desired pressure when discharged from either sleeve 0 or sleeve P. Prior to use of the pump, the housing halves L-l and L-2 are assembled in the manner shown in FIGURE 2, and sleeves O and P are rigidly held in the appropriate positions shown, with the flanged cylinders K-l and K-2 being fixedly mounted on the housing by means of bolts 140 (FIGURE 1). The source of rotational power for crankshaft A should preferably rotate the shaft and rotor B in a counterclockwise direction when the invention is positioned as shown in FIGURE 3.

In this explanation of the operation of the invention it will be assumed that it is initially desired to draw fluid into the confines of the housing through the first fluidcarrying sleeve 0, and discharge the fluid under pressure at a desired rate from the second fluid-carrying sleeve P. Hydraulic fluid under pressure from a source (not shown) is discharged to one of the bores 146 is either flanged cylinder K-1 or K.2 with concurrent discharge of fluid from the other of the cylinders to dispose the slide block in a desired position as shown in FIGURE 3, where the interior of circular member G and the interior surface of ring E are eccentrically located relative to the circum I ferential exterior surface of rotor B. When the pump is first used and shaft A rotated, the blades D are initially moved outward by centrifugal force, but as fluid pressure builds up in the second compartment N, fluid enters the bore '72 in communication therewith to compress spring '78 and displace ball 76' from seat 74. Thereafter this fluid under pressure flows through groove 72 into slots C to force blades D radially outward. Due to the eccentric positioning of rotor B relative to ring E, the hydraulic force thereon moves the blades D radially outward as each blade approaches the first fluid-carrying sleeve 0. When blades D are thus outwardly disposed, together with the exterior circumferential surface of rotor B and the interior surface of ring E, they co-operatively define arcuate pockets or spaces S that move the fluid being pumped toward the second fluid-carrying sleeve P.

As rotor B rotates in a counter clockwise direction, fluid is carried into space S from the first compartment M to compartment N by positive displacement. As a result of the continuous discharge of fluid thereinto, pressure builds up in compartment N to cause fluid in this compartment to discharge therefrom through the second fluidcarrying sleeve P. It will be apparent that the rate of discharge from sleeve P is dependent not only on the volume of each of the spaces S, but the rate at which rotor B is rotated to sequentially move each space S from compartment M to compartment N as well.

By varying the degree of eccentricity of slide block F relative to rotor B, it is not only possible to control the magnitude of the volume of spaces S, and thus control the rate of discharge from either sleeve 0 or P, but also regulate the direction of fluid flow through pump B. In FIG- URE 3 it will be seen that when slide block F is so disposed relative to rotor B, the volume of spaces S adjacent the second cylinder K4. is greater than that of spaces S adjacent cylinders K'1, whereby more fluid will be carried from compartment M to compartment N than is discharged from second compartment N back to first compartrnent M. Therefore, the fluid pressure in the second compartment tends to increase and fluid will be forced to flow from second sleeve P. As fluid pressure builds up in compartment N, a small portion thereof will flow through bore 72' to compress spring 78 and displace ball 76' from seat 74, and fluid flowing into groove 62 and slots C maintains blades D in pressure contact with the interior surface of ring E. As soon as the fluid pressure on each side of ball 76 is equalized, spring '78 will return ball 76 to a fluid-sealing position on seat 74'. By moving slide block F toward cylinder K-l, the rate of fluid discharge from compartment M to compartment N is not only reduced, but after the volume of spaces S adjacent cylinder K-2 becomes less than that of spaces S adjacent cylinder K-l, more fluid is discharged from compartment N than is discharged thereto from compartment M. Accordingly, the direction of fiow through the pump is from second sleeve P to first sleeve 0.

In many industrial applications, such as actuation of a hydraulically operated oil well pumping unit, it has been found desirable to supply fluid under pressure to rams that move the sucker rod upwardly at a desired rate until the peak of the stroke is reached. Depending upon the operating conditions of the well (not shown), it may then be desirable to lower the sucker rod at either a slower or faster rate than during the raising thereof. This second phase of the operation is easily accomplished by means of the present invention. After the pumping or other reciprocating machine has reached the peak of its upstroke, a valve or other mechanism (not shown) is tripped to cause fluid discharge to cylinder K-Z, and fluid is concurrently permitted to discharge from cylinder K-l through the tapped bore 146 formed in flange 134 forming a part thereof.

The slide block F then moves a desired amount toward cylinder K-l, with the magnitude of the spaces S adjacent cylinder K4 being greater than that of the spaces S adjacent cylinder K-2. Use of hydraulic fluid under pressure to move pistons H is convenient, but it will be apparent that other power means may be employed if desired, such as various mechanical power-operated linkages, or electrical devices such as solenoids, motor and the like. Thereafter fluid is discharged from compartment N to compartment M with the rate of discharge depending not only on the magnitude of the spaces moving toward and away from compartment N, but upon the rate of rotation of rotor B by the power-driven shaft A as well. It will be particularly noted that fluid can only escape from compartment N to compartment M upon positive displacement thereof from the second compartment intothe spaces moving away therefrom. Hence, the rate at which fluid discharges from sleeve P through housing L is easily controlled. This is of particular importance when, as previously mentioned, it is desired to lower the sucker rod at either a slower or faster rate than that at which it was raised, or in various industrial applications wherein it is desired to have a reciprocal member move at a desired rate in one direction, and return in the opposite direction at a different rate.

The balance of the pump operation has been described in detail hereinabove and need not be repeated.

A modification of the pump structure above described is to form the ring E with at least one transversely ex tending recess Y, as may best be seen in FIGURE 3. This recess is positively engaged by one of the blades D as it is moved outwardly, to at all times lock blades D and ring E together as an integral unit, yet with the ring B being eccentrically movable relative to rotor B along an axis Z on which pistons H are longitudinally aligned.

Although my invention is fully capable of achieving the results and providing the advantages hereinbefore mentioned, it is to be understood that it is merely the presently preferred embodiment thereof, and that I do not mean to be limited to the details of construction above described other than as defined in the appended claims.

I claim:

1. In a variable displacement pump the combination of: a shaft; a cylindrical rotor rigidly aflixed to said shaft; a plurality of rectangular rigid blades slidably mounted in a plurality of circumferentially spaced, radially disposed slots formed in said rotor that extend inwardly from the periphery thereof; a rigid ring having an internal diameter greater than that of said rotor which said ring surrounds and which is engageable by the outer ends of said blades to define a succession of armate spaces therebetween; a slide block that includes a circular member in which said ring is rotatably mounted and two diametrically opposed pistons which extend outwardly from said members; first and second cylinders in which said first and second pistons are slidably and sealingly mounted; first and second fluid-carrying sleeves; a hollow cylindrical housing comprising two parallel, laterally spaced side walls having a ring-shaped flange extending between the outer circumferential edges thereof, said side walls being formed with centrally disposed openings through which said shaft extends when said rotor is positioned within said housing, which flange sealingly supports said first and second cylinders and said first and second sleeves in spaced relationship, said first and second cylinders being in diametric alignment and said first and second sleeves being disposed on opposite sides of said second cylinder, with both of said side walls having inwardly projecting portions that extend between said first and second cylinders and are at all times slidably engaged by opposite side surfaces of said rotor, blades, ring and circular member, with said housing being internally divided by said engagement into a first compartment communicating with said first sleeve and a second compartment communicating with said second sleeve; elongate sealing means mounted on said first and second pistons, with the major dimensions of said sealing means being parallel to the longitudinal axes of said pistons, which sealing means extends into said circular member, and which sealing means are in pressure fluid-sealing contact with sections of said projecting portions of said side walls and sections of the interior surfaces of said cylinders; fluid passage means capable of supplying fluid under pressure from said compartments to the inner end portions of said slots to force and maintain said blades into pressure contact with said ring to define said spaces; and pressure means to supply fluid to and discharge fluid from the outwardly disposed portions of said cylinders to move said slide block and ring relative to said rotor and blades, with said shaft when driven in a direction to rotate said blades passing said first sleeve toward said second sleeve causing positive displacement of fluid admitted into said first com- I partment through said first sleeve to said second compartment so long as the volume of said spaces adjacent said second piston is greater than that of said spaces adjacent said first piston, but with the direction of fluid flow being reversed toeffect positive fluid displacement from said second compartment to said first compartment to discharge therefrom through said first sleeve when the volume of said spaces adjacent said first piston is greater than that of said spaces adjacent said second piston.

2. A variable displacement pump as defined in claim 1 wherein said sealing means comprise four elongate bars that are snugly but transversely slidable in four slots formed on opposite sides of said first and second pistons and sections of said circular member adjacent thereto, with each of the two most adjacent slots being connected by at least one transverse bore formed in said piston wherein said two most adjacent slots are located, and a plurality of pressure means are provided in said transverse bores that urge said bars on each of said pistons into said fluid-sealing contact with equal force.

3. A variable displacement pump as defined in claim 1 wherein said longitudinally extending sealing means comprise four elongate bars that are snugly but transversely slidable in four slots formed on opposite sides of said first and second pistons and sections of said circular member adjacent thereto, with said slots in said first and second pistons being connected by a plurality of transversely disposed bores formed in said pistons, and a plurality of compressed first helical springs are disposed in said transverse bores that at all times urge said 9 bars into said pressure fluid-sealing contact with equal force.

4. A variable dispalcement pump as defined in claim 1 wherein said rotor, blades, ring and slide block are of substantially the same width, said inwardly projecting portion of each of said side walls comprises a centrally disposed boss having two arms extending in opposite directions therefrom to said portions of said flange in which said cylinders are positioned, with said openings in said side walls being bores of substantially greater transverse cross section than that of said shaft which extends therethrough, and two cylindrical bearings are disposed in said bores in said bosses on opposite sides of said rotor to rotatably support said shaft.

5. A variable displacement pump as defined in claim 4 including the further elements of two second compressed helical springs that encircle portions of said shaft adjacent said bearings, two fluid-sealing collars which sealingly engage said shaft outwardly from said bearing, with each of said second springs having one end thereof abutting against one of said bearings and the opposite end thereof bearing against one of said collars, which springs, collars and bearings cooperatively maintain said rotor and blades in a centered position within said housing, and holding means that maintain said collars in fixed transverse position relative to said housing when subjected to compression by said second springs.

6. A variable displacement pump as defined in claim 5 wherein said housing comprises two interlocking halves that may be disposed in fluid-sealing, abutting contact and means is provided to removably maintain said halves in said fluid-sealing, interlocking abutment to define said housing.

7. A variable displacement pump as defined in claim 6 wherein said holding means comprises two rigid plates having bores formed therein through which said shaft extends when said plates are disposed in parallel abutting contact with the exterior surfaces of said side walls, which plates have a plurality of spaced bolt holes formed therein that are alignable with a plurality of tapped bores formed in said side walls, and a plurality of bolts are provided that extend through said bores in said plates to threadedly engage said tapped bores and removably hold said plates on said side walls.

8. A variable displacement pump as defined in claim 6 wherein each of said housing halves includes one of said side walls and a portion of said flange, said flange portions having diametrically aligned first and second semicylindrical grooves formed therein which receive said cylinders when said flange portions are in abutment, said circular member has two oppositely disposed guide blocks that project therefrom and define guide surfaces which are parallel to the diametrically disposed axis with which said cylinders are longitudinally aligned, two pressure plates that are at all times in parallel sliding contact with said guide blocks, and adjustment means are movably mounted on said flange portions which support said pressure plates for movement normal to said axis to adjust said guide blocks as required and maintain said slide block in such relationship with said housing that said pistons are longitudinally aligned relative to said cylinders.

9. A variable displacement pump as defined in claim 8 wherein the abutting surfaces of said flange portions between said semi-cylindrical grooves are formed with engaging and engageable portions that interlock when said flange portions are in abutment, and at least one of said abutting surfaces of said flange portions have an arcuate recess formed therein, and resilient sealing means are provided that are disposed in said arcuate recess in pressure fluid-sealing contact with the other of said abutting surfaces of said flange portions to establish a fluid seal therebetween.

10. A variable displacement pump as defined in claim 9 wherein one of said flange portions has a plurality of spaced bores extending transversely therethrough that are 1Q alignable with a plurality of spaced transversely disposed tapped bores formed in the other of said flange portions, and a plurality of bolts are provided that extend through said bores in said flange portions to engage said tapped bores in the other of said flange portions to removably hold said housing halves together to define said housing.

11. A variable displacement pump as defined in claim 10 wherein said pistons have at least one longitudinally extending groove formed therein, and a plurality of resilient sealing members are disposed in said grooves, which members are at all times in pressure fluid-sealing contact with the interior surfaces of said cylinders.

12. A variable displacement pump as defined in claim 11 wherein transversely disposed flanges are aflixedto the outer extremities of said cylinders, each of which flanges has an outwardly projecting boss formed therein through which a centrally disposed longitudinally aligned bore extends as well as a second tapped bore, said second tapped bore being adapted to threadedly receive a threaded fitting through Which fluid is discharged into and out of one of said cylinders to move said slide block and ring relative to said rotor and blades, each of said flanges having a plurality of spaced bore holes extending therethrough that are alignable with tapped bore holes formed in said flange portions, a plurality of bolts which extend through said bore holes in said flanges to engage said tapped bore holes in said flange portions to removably maintain said cylinders in fixed positions on said housing, and two threaded members are provided that have heads, which threaded members engage said first bores with at least portions of said heads projecting into said cylinders to act as stops to limit the outward movement of said pistons, said threaded members being of such length as to project outwardly from said bosses, with lock nuts engaging said outwardly projecting portions of said threaded members to hold same in fixed longitudinal relationship with said flanges.

' 13. A variable displacement pump as defined in claim 12 wherein each of said cylinders has at least one circum ferentially extending groove formed therein and a plurality of resilient sealing members are provided that are disposed in said grooves in said cylinders and are at all times in pressure fluid-sealing contact with the surfaces defining said first and second grooves in said flange portions, each of said sleeves have at least one circumferentially extending groove formed therein, and a plurality of resilient members are disposed in said grooves in said sleeves, which members are at all times in pressure fluid-sealing contact with the surfaces defining third and fourth grooves in said flange portions.

14. A variable displacement pump as defined in claim 13 wherein at least one of said surfaces defining said third and fourth grooves has a longitudinally extending first slot formed therein, each of said sleeves is formed with a second longitudinally extending slot in the exterior surface thereof that is alignable with said first slot, a plurality of rigid members is provided, each of which is removably disposable in an adjacent pair of said first and second slots, which members when so disposed with said flange portions in abutting contact prevent rotation of said sleeves relative to said flange portions, and two ring-shaped members are provided that have threads formed on the interior surface thereof whioh engage said threads on portions of said sleeves projecting from said housing, which ring-shaped members when tightened on said threads draw said sleeves outwardly relative to said flange portions to tightly hold same together as an integralunit.

-15. In a variable displacement pump, the combination of a shaft; a cylindrical rotor rigidly afiixed to said shaft; a. plurality of rectangular rigid blades slidably mounted in a plurality of circumferentially' spaced, radiallydisposed slots that extend inwardly from the periphery of said rotor; a rigid ring having an internal diameter greater than that of said rotor which said ring surrounds and which is engageable by the outwardly disposed ends of said blades to define a succession of 'arcruate spaces therebetween; a

slide block that includes a circular member in which said ring is rotatably mounted and two diametrically opposed pistonsthat extend outwardly from said member; first and second cylinders in which said first and second pistons are slidably and sealingly mounted; first and second fluidcarrying sleeves; a hollow cylindrical housing comprising two parallel, laterally spaced side walls and a ring-shaped flange extending between the outer circumferential edges of said side 'walls, said side walls being formed with centrally disposed openings through which said shaft extends when said rotor is positioned inside said housing, which flange sealingly supports said first and second cylinders in diametric relationship, said first and second sleeves are disposed on opposite sides of said second cylinder, with said side Walls having inwardly projecting portions that extend between said first and second cylinders and are at all times slidably engaged by side surfaces of said rotor, blades, ring and circular member, and as a result of said engagement said housing is internally divided into a first compartment communicating with said first sleeve and a second compartment communicating with said second sleeve; elongate sealing means mounted on said first and second pistons, with the major dimensions of said sealing means being parallel to the longitudinal axes of said pistons, which sealing means extend into said circular member, and which sealing means are in pressure fluidsealing contact with sections of said projecting portions of said side walls and the interior surfaces of said cylinders; two independent fluid passage means communicating with said first and second compartments and two oppositely disposed circular grooves formed on said inwardly projecting portions of said side walls, which circular grooves are at all times in communication with said slots; two spring-loaded check valves communicating with said fluid passage means, said check valves being so loaded as to admit fluid under pressure from said first and second compartments into said circular grooves and said slots to move said blades outwardly into contact with said ring, but said check valves preventing escape of said fluid under pressure from said circular grooves and said slots to said first and second compartments; and pressure means to supply fluid to and discharge fluid from said cylinders to move said slide block and ring relative to said rotor and blades, with said shaft when driven in a direction to rotate said blades passing said first sleeve toward said second sleeve causing positive displacement of fluid admitted into said first compartment through said first sleeve to said second compartment so long as the volume of said spaces adjacent said second piston is greater than that of said spaces adjacent said first piston, but with the direction of fluid flow being reversed to elfect positive fluid displacement from said second compartment to said first compartment when the volume of said spaces adjacent said first piston is greater than that of said spaces adjacent said second piston.

16. A variable displacement pump as defined in claim 15 wherein said ring has at least one transversely disposed recess formed on the interior surface thereof, which recess is capable of being engaged by the outer end portion of one of said blades to positively lock said ring and blades together as said blades move outwardly relative to said ring.

References Cited in the file of this patent UNITED STATES PATENTS 1,943,929 Rayburn Jan. 16, 1934 1,988,213 Ott Jan. 15, 1935 2,238,062 Kendrick Apr. 15, 1941 2,469,097 Wrenn May 3, 1949 2,538,194 Ferris Jan. 16, 1951 2,612,114 Ernst Sept. 30, 1952 2,685,255 Carner Aug. 3, 1954 2,764,941 Miller et al Oct. 2, 1956 2,782,724 Humphreys Feb. 26, 1957 2,809,594 Orshansky Oct. 15, 1957 2,821,928 Wagner Feb. 4, 1958 

1. IN A VARIABLE DISPLACEMENT PUMP THE COMBINATION OF: A SHAFT; A CYLINDRICAL ROTOR RIGIDLY AFFIXED TO SAID SHAFT; A PLURALITY OF RECTANGULAR RIGID BLADES SLIDABLY MOUNTED IN A PLURALITY OF CIRCUMFERENTIALLY SPACED, RADIALLY DISPOSED SLOTS FORMED IN SAID ROTOR THAT EXTEND INWARDLY FROM THE PERIPHERY THEREOF; A RIGID RING HAVING AN INTERNAL DIAMETER GREATER THAN THAT OF SAID ROTOR WHICH SAID RING SURROUNDS AND WHICH IS ENGAGEABLE BY THE OUTER ENDS OF SAID BLADES TO DEFINE A SUCCESSION OF ARCUATE SPACES THEREBETWEEN; A SLIDE BLOCK THAT INCLUDES A CIRCULAR MEMBER IN WHICH SAID RING IS ROTATABLY MOUNTED AND TWO DIAMETRICALLY OPPOSED PISTONS WHICH EXTEND OUTWARDLY FROM SAID MEMBERS; FIRST AND SECOND CYLINDERS IN WHICH SAID FIRST AND SECOND PISTONS ARE SLIDABLY AND SEALINGLY MOUNTED; FIRST AND SECOND FLUID-CARRYING SLEEVES; A HOLLOW CYLINDRICAL HOUSING COMPRISING TWO PARALLEL, LATERALLY SPACED SIDE WALLS HAVING A RING-SHAPED FLANGE EXTENDING BETWEEN THE OUTER CIRCUMFERENTIAL EDGES THEREOF, SAID SIDE WALLS BEING FORMED WITH CENTRALLY DISPOSED OPENINGS THROUGH WHICH SAID SHAFT EXTENDS WHEN SAID ROTOR IS POSITIONED WITHIN SAID HOUSING, WHICH FLANGE SEALINGLY SUPPORTS SAID FIRST AND SECOND CYLINDERS AND SAID FIRST AND SECOND SLEEVES IN SPACED RELATIONSHIP, SAID FIRST AND SECOND CYLINDERS BEING IN DIAMETRIC ALIGNMENT AND SAID FIRST AND SECOND SLEEVES BEING DISPOSED ON OPPOSITE SIDES OF SAID SECOND CYLINDER, WITH BOTH OF SAID SIDE WALLS HAVING INWARDLY PROJECTING PORTIONS THAT EXTEND BETWEEN SAID FIRST AND SECOND CYLINDERS AND ARE AT ALL TIMES SLIDABLY ENGAGED BY OPPOSITE SIDE SURFACES OF SAID ROTOR, BLADES, RING AND CIRCULAR MEMBER, WITH SAID HOUSING BEING INTERNALLY DIVIDED BY SAID ENGAGEMENT INTO A FIRST COMPARTMENT COMMUNICATING WITH SAID FIRST SLEEVE AND A SECOND COMPARTMENT COMMUNICATING WITH SAID SECOND SLEEVE; ELONGATE SEALING MEANS MOUNTED ON SAID FIRST AND SECOND PISTONS, WITH THE MAJOR DIMENSIONS OF SAID SEALING MEANS BEING PARALLEL TO THE LONGITUDINAL AXES OF SAID PISTONS, WHICH SEALING MEANS EXTENDS INTO SAID CIRCULAR MEMBER, AND WHICH SEALING MEANS ARE IN PRESSURE FLUID-SEALING CONTACT WITH SECTIONS OF SAID PROJECTING PORTIONS OF SAID SIDE WALLS AND SECTIONS OF THE INTERIOR SURFACES OF SAID CYLINDERS; FLUID PASSAGE MEANS CAPABLE OF SUPPLYING FLUID UNDER PRESSURE FROM SAID COMPARTMENTS TO THE INNER END PORTIONS OF SAID SLOTS TO FORCE AND MAINTAIN SAID BLADES INTO PRESSURE CONTACT WITH SAID RING TO DEFINE SAID SPACES; AND PRESSURE MEANS TO SUPPLY FLUID TO AND DISCHARGE FLUID FROM THE OUTWARDLY DISPOSED PORTIONS OF SAID CYLINDERS TO MOVE SAID SLIDE BLOCK AND RING RELATIVE TO SAID ROTOR AND BLADES, WITH SAID SHAFT WHEN DRIVEN IN A DIRECTION TO ROTATE SAID BLADES PASSING SAID FIRST SLEEVE TOWARD SAID SECOND SLEEVE CAUSING POSITIVE DISPLACEMENT OF FLUID ADMITTED INTO SAID FIRST COMPARTMENT THROUGH SAID FIRST SLEEVE TO SAID SECOND COMPARTMENT SO LONG AS THE VOLUME OF SAID SPACES ADJACENT SAID SECOND PISTON IS GREATER THAN THAT OF SAID SPACES ADJACENT SAID FIRST PISTON, BUT WITH THE DIRECTION OF FLUID FLOW BEING REVERSED TO EFFECT POSITIVE FLUID DISPLACEMENT FROM SAID SECOND COMPARTMENT TO SAID FIRST COMPARTMENT TO DISCHARGE THEREFROM THROUGH SAID FIRST SLEEVE WHEN THE VOLUME OF SAID SPACES ADJACENT SAID FIRST PISTON IS GREATER THAN THAT OF SAID SPACES ADJACENT SAID SECOND PISTON. 